Imaging medical devices use ionizing radiation in order to produce analyzable image data, such as e.g. computer tomographs or fluoroscopy devices. A fundamental aim is, wherever possible, to expose patients to only such a radiation dose that is absolutely essential in order to be able to guarantee an adequate image quality. The radiation dose to be applied and the image quality are in a competing relationship, so that the radiation dose is to be defined in each case through consideration of both aspects, which hinders an automatic control of the radiation dose. The dose definition is an important preparatory step in the planning, performance and/or control of the device in a radiotherapeutic or nuclear medical procedure.
Along with the consideration of how much of a dose reduction is achievable without having to accept interfering losses in image quality, the user is confronted with a multiplicity of examination parameters. Dose measurements are modality-specific measurement or estimation methods (e.g. for CT: volume CT dose index (CTDIvol), and dose length product (DLP); for fluoroscopy: dose area product (DAP), kerma area product (KAP), cumulative air kerma (CAK), and entrance surface dose (ESD) etc.). The effects of changes in one or more of these parameters on the image quality and dose often cannot be evaluated in a straightforward manner by the user. Moreover, there are manufacturer-specific parameters, the technical background of which is often not known in detail to the user. Dose optimization is also dependent on the type of imaging examination (modality employed and type of examination, such as e.g. thorax CT and abdomen CT).
In known methods, given this complexity, radiologists often rely on heuristics and empirical values in the creation of examination protocols. However, the quality assurance measures usable here are unfortunately very restricted. It is thus possible to implement institution-related quality assurance measures whereby, for example, radiologists define institution-related standards for examination protocols which are based on published studies of leading centers. However, all of these measures use either general (rather than case-specific) heuristics, concentrating on specific examination types or the evaluation of the dose (distribution) on the basis of phantom-based measurements (model-based dose measurements under controlled conditions that do not take into account the patient constitution and take only restricted account of anatomical structure details).
A patient-oriented, patient-specific and case-specific prediction and optimization of examination parameters for dose optimization is possible to a restricted extent only or is not at all possible on this basis. Heuristics allow the dose to be influenced within specific orders of magnitude, i.e. intervals are often indicated for examination parameters or fixed protocols which do not take any account or take only insufficient account of the hardware and software used and the special characteristics of the examination process. A first step in quality assurance often consists in the avoidance of outliers, i.e. of examinations in which an obviously excessively high dose is used and not in a fine-granularity dose optimization. Due to the high complexity of the relevant parameters, it is not possible for many examination variants simply to refer to publications that describe specifically adapted solutions for the current problem (complex combination of examination type, issues involved, patient constitution and equipment type).
Document US 2013/0243300 A1 relates to a system and method for radiographing management which manages radiographing information and provides support services for low-dose radiographing
Document DE 10 2008 002882 A1 relates to the development of strategies for planning medical image data acquisition, the acquisition process, the processing of the image data and the display and visualization depending on access to an electronic patient file.
Document U.S. Pat. No. 8,412,544 B2 relates to a computer-implemented method for measuring a radiation dose and image quality in an imaging examination of a patient.
Document WO 2012/104786 A2 relates to a method which comprises an obtaining of electronically formatted information about previously performed imaging procedures and classifying the information into groups of protocols based on initially selected protocol groups.